# How does sodium carbonate reduce pH?

Sodium carbonate is used in pools to raise pH. From my understanding, it would dissociate in water like so:

$$\ce{Na2CO3 <=> 2 Na+ + CO3^2-}$$

To raise pH, doesn't it have to absorb hydrogen ion/s? If so then wouldn't it just form carbonic acid that would then just dissociate again?

• It's all about equlibrium. Try to write the corresponding equation(s) for hydrolysis and see what dissociates better, sodium hydroxide or hydrocarbonate. Also, the term "to absorb" looks weird in this context. – andselisk Jul 14 at 6:30

You have the equilibrium in water: $$\ce{H2O <=> H+ + OH-}$$ The protons are removed from the equilibrium: $$\ce{H+ + CO3^2- <=> HCO3-}$$ Now you have more $$\ce{OH-}$$ in the solution which increases the pH.